The invention relates to a device for regulating the intensity of an electric current to be supplied to a load and generated by a current/voltage source. The invention also relates to an electrical load.
Electrical loads are often connected directly to the current/voltage supply feeding them. The current path between current/voltage supply and electrical load generally has a specific resistance, which can be increased by additional resistors connected into the current path.
In FIG. 1 an arrangement having electrical load 1 and current/voltage supply 2 is illustrated, the electrical load 1 here being a light-emitting diode (LED), which is connected to the current/voltage supply 2 via a resistor R. The resistor R functions as a current limiter.
The disadvantage with the arrangement described in FIG. 1 is that output fluctuations of the current/voltage supply “break through” directly to the light intensity of the light produced by the light-emitting diode 1. A further disadvantage is that, in the event of a fluctuating output of the current/voltage supply 2, the power loss produced in the light-emitting diode 1, and therefore the temperature prevailing in the light-emitting diode 1, varies highly, which means that the diode 1 has to be designed for a high thermal loadbearing capacity.
In order to counter this problem, it is known to connect a device 3 for regulating the current intensity of the current generated by the current/voltage supply 2 into the current path between the current/voltage supply 2 and the electrical load 1, as illustrated in FIG. 2 (“active current source”). The device 3 has a control circuit for regulating the current intensity, which is integrated into a semiconductor chip 4. The semiconductor chip 4 is mounted on a carrier 5, an insulating layer 6 being provided between the carrier 5 and the semiconductor chip 4. Contact is made with the semiconductor chip 4 on its upper side by means of bonding wires 7, which are connected electrically to connecting legs 8. The entire device 3 is enclosed by a housing 9.
The arrangement illustrated in FIG. 2 has, as already mentioned, the advantage that the light-emitting diode 1 is supplied with a constant input current. However, the fact that the costs of the housing 9 and the costs for mounting the semiconductor chip and the carrier 5 in the housing 9 are relatively high is disadvantageous.
For these and other reasons, there is a need for the present invention.